text: [Co(NH)]Cl is prepared by treating cobalt(II) chloride with ammonia and ammonium chloride followed by oxidation.  Oxidants include hydrogen peroxide or oxygen in the presence of charcoal catalyst.  This salt appears to have been first reported by Fremy.
  The acetate salt can be prepared by aerobic oxidation of cobalt(II) acetate, ammonium acetate, and ammonia in methanol.  The acetate salt is highly water-soluble to the level of 1.9 M (20 °C), versus 0.26 M for the trichloride.